Electric heating assembly

ABSTRACT

An electric heating assembly, wherein a sheathed heating element may be easily assembled with or disassembled from a support. Fluid-tight assembly is effected without the use of a flange fixed to the sheath, or the use of a compression fitting. The sheath extends through an opening in the support, and an O-ring surrounds the sheath and is disposed in a chamber formed by a counterbore of the opening. An insulating member has connection with the support and the terminal of the heating element to hold the sheath against axial movement.

United States Patent 11 1 Temple 3 111 3,772,498 [451 Nov. 13, 1973 1 ELECTRIC HEATING ASSEMBLY [75] Inventor: Sidney J. Temple, Pittsburgh, Pa.

[73] Assignee: Emerson Electric Co., St. Louis, Mo.

[22] Filed: May 3, 1973 [21] Appl. No.: 356,740

[52] US. Cl 21 9/1336, 219/316, 219/318 [51] Int. Cl. H05b 3/04 [58] Field of Search 219/315, 316, 318, -219/335, 336, 523

{56] References Cited UNITED STATES PATENTS 1,506,695 8/1924 Tyler 219/527 X 1,737,834 12/1929 Eaton 219/316 2,799,767 7/1957 Bremer 219/336 3,354,294 11/1967 Kollar et al. 219/336 X Primary Examiner-C. L. Albritton AttorneyMichael Williams [57] ABSTRACT An electric heating assembly, wherein a sheathed heating element may be easily assembled with or disassembled from a support. Fluid-tight assembly is effected without the use of a flange fixed to the sheath, or the use of a compression fitting. The sheath extends through an opening in the support, and an O-ring surrounds the sheath and is disposed in a chamber formed by a counterbore of the opening. An insulating member has connection with the support and the terminal of the heating element to hold the sheath against axial movement.

9 Claims, 8 Drawing Figures 1 ELECTRIC HEATING ASSEMBLY BACKGROUND AND SUMMARY My invention is particularly adapted to secure an end of a sheathed electric heating element in fluid-tight relationship to a flanged cover of a fluid container. Several ways are commonly used to effect such securement. One is to dispose the sheath through a hole in the cover, and weld around the sheath. Another utilized a flanged bushing which was welded to an end of the sheath in fluid-tight relation, the bushing passing through a hole in the cover and having a threaded end extending from the outer surface of the cover. A ring gasket and nut are applied over the threaded end to maintain fluid-tight assembly. Another method of securement consists of welding a threaded plug onto the end of the heating element, and threading the plug into a hole in the cover. v

The foregoing methods provided satisfactory results but had disadvantages from a standpoint of ease of assembly or'replacement of a heating element, and from a standpoint of cost. I

Through use of my invention, the above-mentioned bushings, plug and welding are eliminated. The end of the sheath is simply disposed through a hole in the cover and through an O-ring contained within a counterbore of the hole. A plug closes the counterbore so that the O-ring is maintained within .the chamber formed by the counterbore. Up to this point of assembly, the sheath may be axially moved for assembly and disassembly purposes. To complete the assembly, means are provided to hold the sheath against axial movement.

DESCRIPTION OF THE DRAWINGS In the drawings accompanying this specification and forming a part of this application, there is shown, for purpose of illustration, an embodiment which my'invention may assume, and in these drawings:

FIG. 1 is a plan view of a flanged cover for a fluidcontaining tank, with my invention applied thereto,

FIG. 2 is a fragmentary sectional view corresponding to the line 2--2'of FIG. 1,

FIG. 3 is a fragmentary sectional view similar to FIG. 2, but showing parts in disassembled relation,

FIGS. 4 and 5 are small scale, broken elevational views illustrating two applications of my invention,

FIG. 6 is an enlarged, fragmentary sectional view of a detail, 1

FIG. 7 is a sectional view similar to FIG. 2, but showing a slightly modified construction, and

FIG. 8 is a separated perspective view of a plug used in the construction of FIG. 7, and wrench for turning the plug.

DESCRIPTION OF THE PREFERRED EMBODIMENT applied to a rod-type sheathed element, wherein the latter extends cross-wise ofa tank 12 which may be either closed or open at its upper end. In this case tubular flanges 14 are welded to opposed sides of the tank, and cover plates 15 are bolted thereto.

In either case, the cover or other support 10 is provided with a hole 17 therethrough of a size to closely but slidably pass the sheath 18 of the heating element. FIG. 2 shows a hair-pin type heating element and therefore the support has a pair of holes 17 to pass respective legs of the heating element. FIG. 1 shows use of two hair-pin type heating elements'H and therefore the support 10 would be formed with four holes 17 to receive the legs of the heating elements. It will be understood that more than two hair-pin elements may be carried by the support, depending upon heating requirements. In FIG. 1, the elements are shown connected in series relationship by means of a jumper strap 19. In the installation shown in FIG. 5, each cover or support 15 is provided with only one hole 17, although it may have more if several rod-type elements are used.

With reference to FIGS. 2, 3, and 6, each hole 17 is formed with a counterbore 20 which may have an inclined bottom wall 21. The outer end of the counterbore 20 is provided with internal screw threads 22%0 receive the threaded end 23 of a tubular plug 24. The plug is threaded into the threads 22 so that its end abuts against a shoulder 25. The plug thereby closes the counterbore 20 to form a cylindrical chamber 26 in which a resilient O-ring 27 is confined. The chamber is of an axial length which is.larger than the diameter of the O-ring, so that the latter has limited axial movement therein. The plug 24 has a polygonal head 28 which extends beyond the side surface 29 of the support 10 so that a conventional wrench may be applied thereto.

With the plug 24 turned in against the shoulder 25, theassembly thus far formed will enable the sheath of the heating element to be moved axially, and in this respect the end portion of the element may be completely withdrawn from the hole 17 and replaced by a similar element. As best seen in FIG. 6, the end of the sheath may have its exterior edge rounded, as shown at 30, so that the end portion of the sheath may be freely moved through the support opening 17, O-ring 27 and the opening 31 in the plug 24. In inserting or removing the sheath end portion with respect to the foregoing, the O-ring 27 may roll lengthwise of the chamber 26 and thus not be damaged, or it may merely be compressed, without axial movement. The rounded end 30 of the sheath 1.8 will prevent any damage to the O-ring during assembling operation.

In further assembly, the sheath is held against axial movement by an insulating member which is connected to'the sheath and the support 10. In the disclosed embodiment, the insulating member is shown as a platelike member 35, formed'of a rigid plastic material. The plate member 35 has a small hole 36 adapted to be aligned with the support hole 17 to pass the terminal 37 of the heating element. This terminal is threaded to receive a clamping nut 38 so as to clamp the plate member 35 between it and the end of the sheath, as see in FIG. 2.

The plate member 35 is shown in FIG. 1 as being square and is formed with openings 39 in its four corners to pass the shanks of bolts 40. Sincea space is necessary to accommodate the head 28 of the plug 24, tubular spacers 41 are interposed between the plate member 35 and the side surface 29 of the support 10.

The plate member 35 is rigidly held in position when the shanks of the bolts 40 are threaded into corresponding holes in the support 10.

Thus, with the plate member ridigly held to the support by the bolts 40, and with the sheath end rigidly clamped to the plate member 35 by the clamping nut 38, the sheath is held against axial movement. When no pressure conditions exist in the tanks 11 or 12, the O- ring 27 is compressed sufficiently between the sheath and the wall of the chamber 26 to prevent leakage of fluid. In the event a pressure is built up or exists in the tank, such pressure will follow the arrows shown in FIG. 6 and drive the O-ring 27 against the closure end of the plug 24 with enough force to deform the O-ring into a positive seal to prevent leakage of fluid.

Electrical connections to the terminals of the various heating elements may be made in conventional manner, as seen in FIGS. 1 through 3. In the event a heating element fails or needs to be removed for any reason, it is a simple matter to remove it. In the case of the hairpin element shown in FIGS. 1 through 3, the electrical connections and clamping nuts 38 for each leg of the element are removed. Then the heating element may simply withdraw from the holes 17 of the support. Another heating element may be put into position by a reverse of these operations.

The construction shown in FIG. 7 is substantially similar to that described above, except that the plug 34a is formed without a head and therefore the spacers 41 may be omitted so that the plate-like member 35a lies flush against the support surface 29a. In this case the plug 34a may have cross-slots 44 to receive lugs 45 on the end of a tubular wrench member 46.

I claim:

I. An electric heating assembly for a tank which contains a fluid, comprising;

a support which is connected to said tank, said support having a hole extending therethrough from one side to the other, said hole at one support side being in communication with the interior of said tank and having a counterbore inwardly of the other support side,

a sheathed electric heating element having an outside I diameter to closely-fit through said hole,

a resilient O-ring disposed about said sheath and within said counterbore and in contact with facing surfaces thereof, 7

plug means providing a shoulder which closes said counterbore to form a chamber which contains said O-ring,

and means for holding said sheath against axial movement.

2. The construction according to claim 1 wherein said chamber isaxially longer than the diameter of said Oring so that the latter may shift axially therein.

3. The construction according to claim 1 wherein said heating element has a terminal projecting from an end thereof which is engaged by said means for holding said sheath against axial movement.

4. The construction according to claim 3 wherein an insulating member overlies said support other side and is connected to said support and said terminal.

5. The construction according to claim 4 wherein said insulating member is plate-like and has one side surface facing said support other side and against which said heating element end abuts to limit axial movement of said sheath in one direction, said terminal projecting through a hole in said insulating member and having a head which abuts the opposite side of said insulating member to limit axial movement of said sheath in an opposite direction.

6. The construction according to claim 5 wherein said terminal is formed with screw threads, and a nut is threaded on said terminal to form said head.

7. The construction according to claim 4 wherein said insulating member is bolted to said support.

8. The construction according to claim 7 wherein said plug means has a polygonal head for a wrench, said plug head projecting from said support other side, and spacer means between said support other side and said one side surface of said insulating member to provide space to accomodate said plug head.

9. The construction according to claim 6 wherein said chamber is axially longer than the diameter of said O-ring so that the latter may shift axially therein. 

1. An electric heating assembly for a tank which contains a fluid, comprising; a support which is connected to said tank, said support having a hole extending therethrough from one side to the other, said hole at one support side being in communication with the interior of said tank and having a counterbore inwardly of the other support side, a sheathed electric heating element having an outside diameter to closely fit through said hole, a resilient O-ring disposed about said sheath and within said counterbore and in contact with facing surfaces thereof, plug means providing a shoulder which closes said counterbore to form a chamber which contains said O-ring, and means for holding said sheath against axial movement.
 2. The construction according to claim 1 wherein said chamber is axially longer than the diameter of said O-ring so that the latter may shift axially therein.
 3. The construction according to claim 1 wherein said heating element has a terminal projecting from an end thereof which is engaged by said means for holding said sheath against axial movement.
 4. The construction according to claim 3 wherein an insulating member overlies said support other side and is connected to said support and said terminal.
 5. The construction according to claim 4 wherein said insulating member is plate-like and has one side surface facing said support other side and against which said heating element end abuts to limit axial movement of said sheath in one direction, said terminal projecting through a hole in said insulating member and having a head which abuts the opposite side of said insulating member to limit axial movement of said sheath in an opposite direction.
 6. The construction according to claim 5 wherein said terminal is formed with screw threads, and a nut is threaded on said terminal to form said head.
 7. The construction according to claim 4 wherein said insulating member is bolted to said support.
 8. The construction according to claim 7 wherein said plug means has a polygonal head for a wrench, said plug head projecting from said support other side, and spacer means between said support other side and said one side surface of said insulating member to provide space to accomodate said plug head.
 9. The construction according to claim 6 wherein said chamber is axially longer than the diameter of said O-ring so that the latter may shift axially therein. 